A critical problem in the rotary internal combustion engine known as the Wankel engine, has been the provision of a sufficiently gas-tight and durable seal between the housing stator and the lobes of the rotor. The lack of a sufficiently durble seal has greatly retarded the introduction of such high-speed engines of medium and large chamber capacity and power. Such engines hitherto attemptedly produced have rapidly destroyed their seals so that leakage soon occurs between the stator and rotor surfaces with the result that the engine has quickly lost power and has become unacceptable to purchasers and unreliable in operating life.